A controversial Italian scientist said yesterday that he was behind a secretive network of international researchers claiming to have created the world's first cloned human embryos.

In an interview with the French newspaper Le Monde, Dr Severino Antinori, a fertility expert based in Rome, claimed that two women in Russia and a third in an undisclosed country had become pregnant with embryos produced by a similar technique to that which created 'Dolly the Sheep'. Another woman in Russia had undergone a false pregnancy, he added.

In recent weeks Antinori has made several remarks alluding to being 'aware' of three pregnancies in different countries that had resulted from human cloning techniques. He has also been evasive about his personal connection with the human cloning project. On a recent visit to Rome's Foreign Press Club he denied any direct involvement in the cloning, saying he was merely the project's scientific coordinator.

Having announced the successful creation of cloned human embryos at a medical conference in the United Arab Emirates last month, he promptly denied his own involvement. 'I am not involved in any way,' he said, appearing on a popular current affairs talk show on Italian television in April.

Last week, however, he was challenged directly about whether he was implicated in the three claimed pregnancies involving cloning.

Speaking at a scientific conference in Italy last week, Antinori, whose previous claims have been greeted with scepticism by scientists, confirmed that he was 'effectively behind the network of specialists' involved in the attempts to clone a human. He said the network included American biologist Panos Zavos and 'two renowned British researchers' who 'wished to remain anonymous'.

Antinori added that his group had 'taken into account the fact that certain countries... did not forbid the use of this technique in their jurisdiction'.

Although Antinori has often been presented as being a lone, rogue figure in the scientific community, last week's conference allowed him to demonstrate that he has succeeded in winning over other scientists.

Amid signs of a growing split among scientists over the issue of human cloning research, Antinori is creating a new international grouping of scientists - the World Association of Reproductive Medicine, which he has set up with Paul Dmowsky of the US, Izu Eibschitz of Israel and Chicago-based Yuri Verlinsky - to push for wider experimentation in human cloning.

Meanwhile, the controversy over experiments in human cloning widened this weekend with the revelation that a researcher at the University of California had unsuccessfully attempted to clone human embryos in secret before moving his research to England last year.

Following a Freedom of Information request by the Wall Street Journal, the university confirmed on Friday that geneticist Roger Pedersen and his colleagues had attempted to produce a cloned embryo for therapeutic stem cell research in a privately funded research project but had not succeeded in producing any viable human embryos. US Federal law bans any public funding for human cloning experiments.

Although British scientists remain deeply suspicious of Antinori's work, his latest comments reveal the extraordinary lengths to which dissident scientists are prepared to go to evade proscriptions on human cloning research.